An optical time domain-reflectometer (OTDR) is an optoelectronic instrument that identifies characteristics of optical fibers. The OTDR sends pulses (i.e., optical signals) through the optical fiber that is being tested. The pulses pass every point in the fiber and will cause return pulses or reflections, known as Rayleigh backscattering, at each point/location based on local fiber characteristics. The time that each reflection is received by a receiver in the OTDR correlates to the location where each reflection happens.
OTDR measurements of the fiber reflections may be analyzed to determine whether there are discontinuities in different locations of the optical fibers. The strength of the return pulses may be integrated as a function of time. The OTDR may identify fiber signal attenuation and discontinuous loss events. Technicians may be deployed to locations along the optical fiber to fix the issues in the optical fiber.